# AP Chemistry 1.4 Laws of Thermodynamics

AP Chemistry 1.4 Laws of Thermodynamics. Which of the following statements is true?

 AP Chemistry Laws of ThermodynamicsThe Laws of Thermodynamics Language English Language

### Transcript

00:21

If the temperature of A increases by 3 °C, and the temperature of B increases by 6 °C,

00:27

which of the following statements is true?

00:29

And here are our potential answers: These must be some creepy substances… [Gas appears]

00:36

Absorbing all this energy like dementors swallowing your soul… somebody should cast a patronus [Dementor appears]

00:42

charm, quick.

00:44

What's that?

00:45

Any object that increases in temperature is absorbing energy?

00:48

Oh….maybe we overreacted a little bit.

00:51

So to solve this problem, let’s take a look at this equation. [Finger points to equation]

00:53

Here, Q is the amount of heat or energy transferred when a material changes temperature, m is

00:59

the material’s mass, Cp is the heat capacity, and delta T is the change in

01:05

temperature.

01:06

We know from the problem statement that substances A and B have the same mass.

01:10

They also both absorb the same amount of energy, 50 joules.

01:14

That means the only factors that can differ between them are the change in temperature [Thermometer rising in temperature]

01:18

and the heat capacity.

01:19

So let’s write that out as an equation, which looks a little something like….this.

01:24

And even though it looks complicated, you don't have to be Hermione Granger to solve

01:28

this one.

01:29

The problem tells us the temperature increase for substance A is 3 degrees Celsius, while [Finger points to temperature increase for substance A]

01:33

the temperature increase for substance B is 6 degrees Celsius.

01:37

If we reduce this equation and cancel out the units, we can see that the heat capacity

01:41

of material A is twice the heat capacity of material B. And that just happens to be answer

01:46

choice (A).

01:48

Well done. [Girl pours potion]

01:49

You know, if you went to Hogwarts, we’re pretty sure you’d be a Ravenclaw, you smarty

01:53

pants.